Molded plastic leaching chambers having arch shape cross section and slotted sidewalls are buried in soil, to receive wastewater, such as from a septic tank, so the water can be percolated into the soil. A popular configuration of widely used chamber is about 6 ft long, about 3 ft wide and 1 to 1.5 ft high. Some specialty chambers, favored for drier and sandier soils are narrower and longer, at about 8 feet. Chambers are connected together at joints, to form a string of chambers within a trench, and then covered with soil or other media. Because water usually flows by gravity into and through a string of chambers, a string must be very close to level. So, the bottom of the trench is prepared accordingly, usually with a mechanical trencher.
To create the string, chambers are sequentially placed in a trench, which is slightly wider than the chamber width. Typically, chambers interlock together to with some kind of load-transferring inter-chamber joints, as by means of overlapping male and female flanges. See U.S. Pat. No. 5,336,017. Installing the string requires some skill and practice. Typically, a worker cants a second chamber upwardly, as he stands in the empty part of the trench, just beyond a previously installed first chamber. He seeks to engage the features at the first end of the second chamber with the mating details at the end of the first chamber. With the chambers partially engaged, he angles down the second end of the second chamber to a level position, while applying lateral pressure to keep the joint together. The installer's vision of the joint is often impaired by the bulk of the chamber, as the installer has to move down the narrow trench while lowering the chamber into the space he vacates.
The typical 6 foot long by 3 foot wide chamber typically weighs 25-40 pounds. It is thus bulky and awkward to handle. Problems with installing chambers arise, particularly when weather conditions are poor or the worker is impatient or unskilled. The trench may be irregular, with sides that are prone to shedding soil and stones into the trench, should the installer hit a side of the trench. Soil falling into the trench can upset the careful leveling of the trench bottom; and, even a small amount of soil can become captured within the joint, upsetting good engagement. Such problems either slow the work or cause the worker to do remedial work. Sometimes, chambers have to be removed so the trench can be re-leveled. Adding an assistant is undesirable because of increase in labor cost. Whenever there are awkward and repetitive motions, or a worker is irritated, there is a potential risk of injury, which one would want to avoid. Lumbar injuries are most associated with lifting bulky or heavy objects at extreme distances from the body. See the book “Designing for Humans”, referenced below. Thus, one aim of the present invention is to ease installation and reduce labor costs.
Another need, which arises when installing chambers, is to make the chambers follow a curved path in the horizontal plane. Sometimes, the contour of a slope must be followed, or minor obstructions lie along a straight path. Prior art chambers with ordinary joints designed for essentially linear strings have a some angular flexibility. For instance, a plus or minus 3 degree bend might be achieved in a joint which is basically intended for straight line connection. See U.S. Pat. No. 5,336,017 of Nichols. There are prior art chambers with angled ends. See U.S. Pat. No. 5,588,778 of Nichols et al. But such chambers are basically suited for fixed large angle changes; and, using them presents inventory problems in the manufacturing and distribution system. They have not been favored in commerce. Swivel connections for chambers are known, to address the need. For instance, a joint between chambers running at between plus or minus 10 degrees might be created. See commonly owned U.S. patent application Ser. No. 10/442,810 of J. Burnes et al., filed May 20, 2003 and U.S. Pat. No. 6,592,293 to Hedstrom et al. While such chambers are useful, they add a complexity to the structural design and manufacture. So, it is an aim to alternatively provide for angular variations in the horizontal plane. Additionally, the bottom of the trench may not be precisely planar, and the same limitations and needs apply to vertical plane angling of chambers.
Another problem associated with certain chambers is that chambers are nested for transport, and are difficult to unstack, at the point of use. Lifting one end of a chamber unevenly with the other end, when seeking to remove the chamber from a nested stack, can cause jamming and resistance to separating. Common chambers cannot be grasped and lifted evenly at both ends by an ordinary worker, because of the chamber size compared to work arm spread. So, an undesirable result is that two workers may be required, to lift both ends of a 6 foot long chamber from a stack.
Generally, the ability of a worker to handle chambers depends on the size of the worker relative to the chamber or other article being handled. Women, who are on average smaller and less strong than men, are more commonplace nowadays in construction and other mechanical trades. So, it is a general object to accommodate them, by improving the manner in which inherently large awkward objects can be handled.